<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <title>addLoadEvent</title> </head> <body> <script type="text/javascript">addLoadEvent(firstFunction); addLoadEvent(secondFunction); function firstFunction(){ alert('我是第一个函数'); } function secondFunction(){ alert('我是需要加载的第二个函数'); } function addLoadEvent(func){ var oldonload=window.onload; //把现有的window.onload事件处理函数的值存入变量oldonload if(typeof window.onload !='function'){ window.onload=func; }else{ window.onload=function(){ oldonload(); func(); } } } </script> </body> </html>